Patient monitor capable of monitoring the quality of attached probes and accessories

ABSTRACT

A system and method to help maintain quality control and reduce cannibalization of accessories and attached probes in a highly sensitive patient monitor, such as a pulse oximetry system. One or more attached components may have information elements designed to designate what quality control mechanisms a patient monitor should look to find on that or another component or designate other components with which the one component may properly work. In a further embodiment, such information elements may also include data indicating the appropriate life of the component.

PRIORITY CLAIM

This application is a continuation of U.S. application Ser. No.11/871,817, filed Oct. 12, 2007, entitled “Patient Monitor Capable ofMonitoring the Quality of Attached Probes and Accessories”, which claimspriority to U.S. Provisional Application No. 60/851,788, titled “PatientMonitor Capable of Monitoring the Quality of Attached Probes andAccessories” and filed on Oct. 12, 2006, the disclosure of which isincorporated herein by reference.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.11/640,077, filed on Dec. 12, 2006, which is a continuation of U.S.patent application Ser. No. 10/757,279, filed on Jan. 13, 2004, which isa continuation of Ser. No. 10/005,711, filed on Nov. 8, 2001, now U.S.Pat. No. 6,678,543, which is a continuation of U.S. patent applicationSer. No. 09/451,151, filed on Nov. 30, 1999, now U.S. Pat. No.6,397,091, which is a continuation of U.S. patent application Ser. No.09/016,924, filed on Feb. 2, 1998, now U.S. Pat. No. 6,011,986, which isa continuation of U.S. patent application Ser. No. 08/478,493, filed onJun. 7, 1995, now U.S. Pat. No. 5,758,644, as well as U.S. patentapplication Ser. No. 08/745,474, filed on Nov. 12, 1996, now U.S. Pat.No. 5,823,950, which is a divisional of U.S. U.S. patent applicationSer. No. 08/478,493, filed on Jun. 7, 1995, now U.S. Pat. No. 5,758,644.The present application incorporates the foregoing disclosures herein byreference.

BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

The present disclosure relates in general to noninvasive patientmonitoring systems, including oximeters and co-oximeters, and theiraccessories such as sensors or cables. In particular, this disclosurerelates to patient monitors capable of monitoring the quality ofattached accessories.

Description of the Related Art

Patient monitoring of various physiological parameters of a patient isimportant to a wide range of medical applications. Oximetry is one ofthe techniques that has developed to accomplish the monitoring of someof these physiological characteristics. It was developed to study and tomeasure, among other things, the oxygen status of blood. Pulseoximetry—a noninvasive, widely accepted form of oximetry—relies on asensor attached externally to a patient to output signals indicative ofvarious physiological parameters, such as a patient's constituents oranalytes, including for example a percent value for arterial oxygensaturation, carbon monoxide saturation, methenoglobin saturation,fractional saturations, total hematocrit, billirubins, perfusionquality, or the like

A pulse oximeter sensor generally includes one or more energy emissiondevices, such as specific wavelength emitting LEDs, and one or moreenergy detection devices. The sensor is generally attached to ameasurement site such as a patient's finger, toe, ear, ankle, or thelike. An attachment mechanism positions the emitters and detectorproximal to the measurement site such that the emitters project energyinto the tissue, blood vessels and capillaries of the measurement site,which in turn attenuate the energy. The detector then detects thatattenuated energy. The detector communicates at least one signalindicative of the detected attenuated energy to a signal processingdevice such as an oximeter, generally through cabling attaching thesensor to the oximeter. The oximeter generally calculates, among otherthings, one or more physiological parameters of the measurement site. Insome oximeter systems, specific-valued resistors in the attached sensorprovide the signal processing device specific wavelength (“k”)information for the emitters of the sensor. For example, oximeters thatcapture k information are disclosed in U.S. Pat. No. 4,621,643, entitled“Calibrated Optical Oximeter Probe” and awarded to New, Jr. et al. onNov. 11, 1986, and U.S. Pat. No. 4,700,708, entitled “Calibrated OpticalOximeter Probe” and awarded to New, Jr. et al. on Oct. 20, 1987.

Patient monitors, generally, and oximeter systems specifically are oftenhighly sensitive instruments. This is especially the case in oximetersystems capable of determining physiological parameters during patientmotion, such as those commercially available from Masimo Corporation ofIrvine, Calif., and disclosed generally in U.S. Pat. No. 6,263,222,entitled “Signal Processing Apparatus,” and U.S. Pat. No. 6,157,850,also entitled “Signal Processing Apparatus,” U.S. application Ser. No.09/491,175, entitled “Universal/Upgrading Pulse Oximeter,” and the like,each of which is incorporated herein by reference. The manufacturers ofsuch oximeter systems incorporate into their signal processingalgorithms an expectation of a certain type and quality of electroniccomponents in the cabling and sensors. Often the results produced by thesignal processing, such as, for example, the output values of variousmonitored physiological parameters of the patient, are at least somewhatdependent upon receipt of signals from quality electronic components.Thus, many manufacturers carefully control and manage the type andquality of their sensors and accessories.

However, when other sensor manufacturers lure caregivers into purchasing“compatible” sensors, the oximeter manufacturer loses the ability tocontrol the type and quality of the electronic components, the accuracyof their attachment/placement mechanisms, and the like. This isespecially problematic with knock-off accessories that attempt tostandardize sensor components across differing manufacturers' oximetersystems. For this reason, oximeter manufactures began using theforegoing resistors also as quality control security devices. Forexample, some oximeter systems look for specific-valued resistors withinthe circuitry of their sensors, such as, for example, those resistorsdisclosed in patents entitled “Manual and Automatic Probe Calibration:”U.S. Pat. No. 5,758,644, awarded to Diab et al. on Jun. 2, 1998; U.S.Pat. No. 6,011,986, awarded to Diab et al. on Jan. 4, 2000; and U.S.Pat. No. 6,397,091, awarded to Diab et al. on May 28, 2002. Althoughsuch resistor mechanisms improved manufacturer's quality control, someknock off sensor manufactures unfortunately began copying or otherwisescavenging quality control devices from, for example, expired orauthorized sensors, thus defeating the quality control device of theoriginal oximeter manufacturer.

Additionally upgrades to patient monitor algorithms and specificationsmay be made with the expectation that accessories with different optics,higher fidelity, different specifications or the like will be used. Aquality check in such an instance can help to ensure that any upgradedalgorithms produce more accurate results.

SUMMARY OF THE DISCLOSURE

Based on at least the foregoing, there is a need to provide oximetrysystems capable of monitoring the quality of attached optical probes andaccessories, while reducing the ability of unscrupulous sensormanufacturers to defeat such quality controls. Accordingly, one aspectof the present disclosure is a patient monitoring system for maintainingquality control while reducing a likelihood of defeat of that qualitycontrol, through, for example, cannibalization of quality controldevices from used and possibly damaged authorized sensors. According toan embodiment of the disclosure, an oximetry system includes anoximeter, a sensor, and a connecting cable to connect the sensor to theoximeter. In an embodiment, the cable includes an information elementcapable of storing information. The cable's information element could beprovided through an active circuit such as a transistor network, memorychip, EEPROM (electronically erasable programmable read-only memory),EPROM (erasable programmable read-only memory), or other identificationdevice, such as multi-contact single wire memory devices or otherdevices, such as those commercially available from Dallas Semiconductoror the like. In an embodiment, the oximeter accesses the informationstored on the information element of the cable to determine whether thecable is an authorized cable.

In an embodiment, the oximeter may use the information stored on thecable information element to determine a type of quality control deviceexpected on an attached sensor. For example, one type of information mayadvantageously instruct the oximeter to look for a quality controldevice comprising a sensor identifier, for example, a resistor of aspecified value on the sensor. Another type of information mayadvantageously instruct the oximeter to look for a different qualitycontrol device comprising, for example, a sensor information elementstoring additional identifying information. In the event that theoximeter fails to find one or more of the information element on thecable and the quality control device(s) on the sensor, the oximeter maytake one or more remedial actions, such as, for example, activatingaudio or visual alarms, combinations of the same, or the like. In anembodiment, the oximeter may display an alarm message such as“unrecognized sensor,” “unauthorized sensor” “unrecognized cable,”“unauthorized cable,” or the like.

Another aspect of the present disclosure is a method for testing asensor. The method comprises obtaining first information from a firstinformation element, outputting a signal to the sensor based on thefirst information, receiving one or more responses from the sensor, anddetermining whether the one or more responses from the sensor indicatethe sensor comprises an authorized sensor.

In yet other embodiments, encryption algorithms may advantageouslyencrypt information stored on one or more of the various informationelements and/or encrypt the communication to and from the oximeter. Askilled artisan will recognize from the disclosure herein that a widevariety of simple or complex encryption algorithms, paradigms,methodologies, or a combination of the same could be used to furtherinhibit copyist sensor manufacturers attempting to produce “compatible”sensors outside the quality control of the oximeter provider. Examplescan include the use of translation tables, symmetric or asymmetrickey-based encryption methods, or many other encryption techniques orcombinations known to an artisan of ordinary skill.

In yet a further embodiment, the oximeter may further store informationregarding the useful and safe life of electrical components of, forexample, the sensor, the cabling, or the like. For example, the amountof use of a particular component may advantageously be tracked to reduceoveruse of that component. Monitoring of overuse is especiallyadvantageous in reusable technologies, and may be accomplished, forexample, as disclosed in U.S. Pat. No. 6,515,273 entitled “System forIndicating the Expiration of the Useful Operating Life of a PulseOximetry Sensor,” awarded to Al-Ali, owned by the assignee of thepresent disclosure and incorporated herein by reference. In suchsystems, the oximeter systems may advantageously be capable ofidentifying source-indicating elements in an attached cabling and/orsensor, and how long various sensor elements have been in use. Thus,should an unauthorized sensor manufacturer manage to scavenge some orall of the identifying parts of a used sensor according to thisembodiment, the useful life measurement may advantageously significantlyreduce any extended use of any cannibalized sensor. For example, in someembodiments, the useful life of electronic components of a sensor may bemeasured in weeks of use, thereby significantly limiting the value ofscavenged components to knock-off sensor manufacturers. Reduction ofscavenged value advantageously increases the ability of sensormanufacturers to control the quality of sensor components and oximeteraccessories.

In addition, in another embodiment, attached accessories, such ascabling and/or sensors, may have an information element that can storedata from an oximeter or other patient monitor. In such an embodiment,each oximeter or patient monitor has a software ID. When an accessory isattached, the monitor looks to see if any monitor has written to theaccessory's information element. If not, in an embodiment, the monitorstores its software ID on the accessory. In a possible embodiment, useof an accessory which has had a monitor ID written to it may only beenabled if the accessory is attached to the monitor having the same IDor some defined set of monitors having software IDs in a specific setthat includes the monitor ID written to it.

Yet another embodiment may utilize similar principles in controlling theupgrading of patient monitors. In an embodiment, a patient monitor iscapable of monitoring a wide array of patient parameters, but themonitoring of individual parameters may be enabled or disabled based onthe parameter monitoring licensed to the user. It will be advantageousto allow changes to the enabled parameters without returning the patientmonitor to the manufacturer. In an embodiment, this may be done byconnecting an upgrade tool much like any other accessory discussedherein. In an embodiment, the ability to upgrade a given patient monitoris dependent on an ID on the upgrade tool matching or corresponding toan allowed monitor ID.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the disclosure have been described herein. Ofcourse, it is to be understood that not necessarily all such aspects,advantages or features will be embodied in any particular embodiment ofthe disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings and the associated descriptions are provided toillustrate embodiments of the present disclosure and do not limit thescope of the claims.

FIG. 1 illustrates a perspective view of a typical sensor includingreusable and disposable elements, and a typical cable.

FIG. 1B illustrates the signal flow of an embodiment of a method ofutilizing quality control elements to monitor authorized accessoriesaccording to this disclosure.

FIG. 2 illustrates an exemplary block diagram of an oximetry systemincluding quality control devices, according to an embodiment of thedisclosure.

FIG. 2A illustrates another exemplary block diagram of an oximetrysystem including quality control devices, according to an embodiment ofthe disclosure.

FIG. 3 illustrates another exemplary block diagram of an oximetry systemincluding quality control devices, according to an embodiment of thedisclosure.

FIG. 4 illustrates an exemplary block diagram of an oximetry systemincluding quality control devices, according to an embodiment of thedisclosure.

FIG. 5 illustrates an exemplary block diagram of an oximetry systemincluding quality control devices, according to an embodiment of thedisclosure.

FIG. 6 illustrates an exemplary block diagram of an oximetry systemincluding quality control devices utilizing wireless identificationtechnology.

FIG. 7 illustrates a flow chart of an embodiment of a method utilizingquality control elements to enforce a site license.

DETAILED DESCRIPTION

The present disclosure has applicability to medical probes in generaland is directed toward patient monitors, cabling, sensors, and the like.As discussed above, a patient monitor comprises signal processingcapable of monitoring whether a caregiver or user is attachingauthorized cabling and/or sensors. Such quality control systems aidmonitor manufacturers in ensuring that caregivers such as doctors obtainaccurate data from patient monitors used in applications from generalward, athletic, or personal monitoring to surgical and other potentiallylife-threatening environments, to any other use of noninvasivemonitoring of patient physiologies. Although the present disclosure isapplicable to many different types of patient monitors, some of thisdiscussion will focus on pulse oximeters, as representative embodimentsonly.

In general, a patient monitor may advantageously read a firstinformation element on a first accessory to obtain first quality controlinformation. The first information may advantageously allow the signalprocessor to identify the first accessory, such as a cable, as anauthorized cable. In an embodiment, the patient monitor mayadvantageously read a second information element on a second accessoryto obtain second quality control information. In an embodiment, thefirst information element provides an indication of what the secondquality control information should be. When the first and secondinformation correlates, the patient monitor can be more assured of thequality of the attached accessories. On the other hand, when there is amismatch, various remedial measures may be taken, including displaying amessage of one or more unauthorized accessories, actuating an indicatorlight on one or more of the accessories, or other audible or visualindications of the mismatch.

For example, in an embodiment, a signal processor of a patient monitorcommunicates with a first information element associated with a firstaccessory, and uses the information stored or coded therein to determinea type of information such as a resistance value, expected to be storedor coded into a second information element associated with a secondaccessory. Specifically, the information gained from the firstaccessory, such as a cable, may provide specific resistance value(s) orrange of values expected on the second accessory, such as a sensor. Suchresistance values may be found in parallel with one or more emitters(such as for example, those disclosed in the foregoing '644 patent) oron separate conductors (such as, for example, those disclosed in theforegoing '643 patent). In other embodiments, the information gainedfrom the first accessory provides information usable to access thesecond information element. Communication with the second informationelement on the second accessory advantageously provides the specificresistance value(s) or range of values expected on the sensor.

In another embodiment, the patient monitor may advantageouslyadditionally acquire information indicative of the lifespan, amount ofuse, or age of one or more accessories, including the cable and/or thesensor. In an embodiment, if the patient monitor determines that one ormore accessories have expired, it will inform the user with anappropriate audio or visual message.

Much of this discussion utilizes pulse oximeters and oximeter cable andsensor accessories in explaining the disclosure and for ease ofunderstanding. However, the disclosure herein is not limited thereby.Patient monitors other than oximeters may similarly utilize the ideasdisclosed. Similarly, labeling the first and second accessories as acable and sensor more clearly differentiate the two accessories;however, a skilled artisan will recognize, from the disclosure herein, awide range of uses of cascading security devices for linked or nonlinkedmonitor accessories.

To facilitate a complete understanding of the disclosure, the remainderof the detailed description describes the disclosure with reference tothe drawings. Corresponding numbers indicate corresponding parts, andthe leading digit of any number indicates the figure in which thatelement is first shown.

FIG. 1 shows sensor and cable elements of an oximeter system as isgenerally known in the prior art. The system comprises cable 104connecting sensor 106 to an oximeter 102 (not shown). As shown here, thesensor 106 includes a reusable portion 108, generally includingexpensive electronics, and a disposable portion 110, generally includingpositioning mechanisms such as tape. Male connection housing 112 at oneend of sensor 106 connects sensor 106 to female cable connection 150 ofcable 104. The operation and construction of reusable and disposablesensors is disclosed in U.S. Pat. No. 6,920,345 entitled “Optical SensorIncluding Disposable and Reusable Elements” awarded to Al-Ali and ownedby the assignee of the present disclosure, the full disclosure of whichis incorporated herein by reference. Other disclosure may be found inU.S. Application No. 60/740,541, filed Nov. 29, 2005, also entitled“Optical Sensor Including Disposable and Reusable Elements,”incorporated herein by reference.

FIG. 1B illustrates a patient monitor 102 and attached accessories inaccordance with an embodiment of the disclosure. Specifically, cable 104and sensor 106 each include an information element housed within them(cable information element 116 and second sensor information element134, respectively). The placement of these information elements need notbe as shown in the figure, as will be described in more detail below.FIG. 1B also illustrates the signal flow of an embodiment of a processfor controlling the quality of attached accessories. First, the qualitycontrol process may be initiated when one or more new accessories areattached to the monitor 102; similarly, the process may initiate when amonitor is turned on. Recognizing that an accessory is attached, themonitor searches for cable information element 116 (step 2). Theinformation element 116 then returns a cable authentication code, whichmay be used by the monitor to determine that the cable 104 is a quality,authorized cable (step 3). Based on the cable authentication code, themonitor 102 then searches for a specific sensor information element 134(step 4). If the correct type of information element is found, themonitor retrieves a sensor authorization code (step 5). The monitor canthen compare the cable authorization code and the sensor authorizationcode to determine whether the cable 104 and sensor 106 are matching,quality accessories. If the codes do correlate, the monitor may enablethe system for monitoring of a patient (step 6).

FIGS. 2 and 2A show a block diagram of embodiments of oximeter systemsincluding improved security technologies. Oximeter 102 uses port 252 toconnect to cable 104 at connector 114. Cable 104 in turn uses cableconnector 150 to connect to sensor 106 at connection housing 112. Cable104 includes an information element 116, which may be located anywheretherein, but is pictured in the figures in port connector 114. Cableinformation element 116 is preferably an EEPROM with encrypted data. Inan embodiment, sensor 106 includes LEDs 222 and 224. The first LED 222has a first corresponding electrical connection 220; the second LED 224has a second corresponding electrical connection 228; and thephotodetector 226 has a corresponding electrical connection 232. In theconfiguration shown in FIG. 2, the LEDs 222, 224 are connected at theiroutputs to a common ground electrical connection 230; however, otherconfigurations may advantageously be implemented, such as, for exampleback-to-back (see FIG. 2A), anode, cathode, common anode, commoncathode, or the like. The photodetector 226 is connected to anelectrical connection 233. In accordance with this aspect of the presentdisclosure, one of the LED electrical connections 220 can also be usedfor a first sensor information element 218—placing first sensorinformation element 218 in parallel with one of LEDs 222, 224. In anembodiment, first sensor information element may comprise a codingresistor or other passive element.

According to an embodiment, Oximeter 102 may communicate with cableinformation element 116 which returns data to oximeter 102. In at leastan embodiment such data may be encrypted, and oximeter 102 is able todecrypt the information. In an embodiment, the information designatesadditional information that oximeter 102 may read from attached sensor106, generally from first sensor information element 218. The value ofthe first sensor information element 218 and/or its placement across anLED may be used to help indicate that the probe is configured properlyfor the oximeter. The first sensor information element 218 may beutilized to indicate that the probe is from an authorized supplier suchas a “Masimo” standard probe, “Patient Monitoring Company 1” probe,“Patient Monitoring Company 2” probe, etc. In another embodiment, thefirst sensor information element 218 may be used to indicate LEDwavelengths for the sensor or other parameters of the sensor 106.

In an embodiment, reading of the first sensor information element 218may advantageously be accomplished according to the disclosure of U.S.Pat. No. 6,397,091, entitled “Manual and automatic probe calibration,”awarded to Diab and owned by the assignees of the present disclosure,incorporated herein by reference.

In addition, it should be noted that the cable information element orfirst sensor information element need not be passive elements. Codinginformation could also be provided through an active circuit such as atransistor network, memory chip, or other identification device, forinstance Dallas Semiconductor DS 1990 or DS 2401 or other automaticidentification chip. It is also possible to place the first sensorinformation element 218 in series or in parallel with one of the LEDs222, 224 or with the photodetector 226 on transmission line 233 or placethe first sensor information element 218 apart from all of the LEDs 222,224 and photodetector 226 on its own transmission lines. Otherplacements of the first sensor information element 218 would also beobvious to one of ordinary skill in the art, so long as the coded valueor other data from first sensor information element 218 can bedetermined by oximeter 102.

Another embodiment of an oximeter system having improved securitytechnologies is shown in FIG. 3. In embodiments such as pictured in FIG.3, sensor 106 of the oximeter system additionally has a second sensorinformation element 134. In a preferred embodiment, second sensorinformation element 134 is an EEPROM with encrypted data, but it may beany of a wide variety of active or passive solutions discussed inrelation to first sensor information element and/or cable informationelement. The second sensor information element 134 is attached to thesensor through line 336. Line 336 may preferably be a serial cable orother type of cable that allows two-way transfer of data. In such anembodiment, cable information element 116 of the cable may provideinformation to oximeter 102 that indicates both a first sensorinformation element 218 and a second sensor information element 134should be found and provide information to the oximeter 102. Secondsensor information element 134 may then provide data, encrypted or not,to oximeter 102, such that the data indicates to oximeter 102information about coding values of, or other data stored on, firstsensor information element 218. Oximeter 102 may then obtain and comparethe information from first sensor information element 218 and secondsensor information element 134 to determine the security and reliabilityof sensor 106. If the elements do not correctly designate a singleapproved sensor, an audible and/or visual warning may be triggered. Theaddition of this second information element may serve to tie variousportions of a single accessory, such as a sensor, together, therebymaking it more difficult for a knock off manufacturer to scavenge parts,particularly if the parts are discarded separately. Alternatively,information from the cable information element 116 may indicate that anattached oximeter 102 should look for second sensor information element134. Information contained in second information element 134 may thenindicate whether or not a first sensor information element 218 ispresent and/or what data should be included thereon to indicate anauthorized sensor.

In various embodiments, second sensor information element 134 mayadvantageously store some or all of a wide variety of information,including, for example, sensor type designation, patient information,sensor characteristics, software such as scripts or executable code,oximeter or algorithm upgrade information, or many other types of data.In a preferred embodiment, the second sensor information element 134 mayalso store useful life data indicating whether some or all sensorcomponents have expired and should be replaced. In such an embodiment,the oximeter 102 may compare the information it received from firstsensor information element 218 and second sensor information element 134as before. Further it may also help aid in determining that sensorelements have not been used longer than their useful life based on thelife data retrieved from second sensor information element 134. In suchan embodiment, the oximeter 102 may also produce an audible or visualalarm if sensor life data from second sensor information element 134indicates that some or all of sensor 106's components are out of date.

Similarly cable information element 116 may also include useful lifedata. This data can be used by oximeter 102 to help reduce the risk thatcable 104 might be used longer than its safe life.

At least some embodiments including second information element 134 mayinclude further protection against cannibalization of parts. Once asensor including second information element 134 is attached andauthorized, the LEDs should be immediately accessible for measurement bythe patient monitor 102. In an embodiment, if at any time the secondinformation element 134 is accessible but the LEDs are not, the patientmonitor 102 may trigger an alert or an alarm and/or may disable the useof the component including the second information element 134. This mayhelp to provide additional quality control protection because if thefirst and second information elements 218, 134 are cannibalized from oldsensors, they are often placed in a generic cable or generic sensoradaptor. This generic adaptor often remains connected while genericsensors are replaced.

FIG. 4 illustrates one potential general layout of the first sensorinformation element 218, cable information element 116, and LEDs 222,224. In such an embodiment, oximeter board 440 is the portion of theoximeter 102 that communicates with the cable 104 and sensor 106. In anembodiment, oximeter board 440 may preferably communicate with cableinformation element 116 via a serial transmission line 446. In FIG. 4,cable information element 116 is located in port connector 114 of thecable 104 in this embodiment. Once oximeter board 440 determines that itis connected to cable 104 providing information indicating that itshould look for first sensor information element 218, it sends andreceives signals down and from transmission lines 442, 444. Transmissionlines 442, 444 pass the length of cable 104 into sensor 106 where firstsensor information element 218 and LEDs 222, 224 are connected inparallel as described in more detail with respect to FIG. 2A.

FIG. 4 shows a possible distribution of the first sensor informationelement 218 and LEDs 222, 224 in the sensor. In the embodiment shown,first sensor information element 218 is located in the connectionhousing 112 where space is generally more readily available (as it isgenerally desirable to keep the sensor volume near the LED emitters 222,224 and photodetector 226 as low as possible). Other placements for theelements, such as the first sensor information element 218 and LEDs 222,224 on sensor 106, are also contemplated by this disclosure. Those ofordinary skill in the art would know that first sensor informationelement 218, for example, could be located anywhere in the sensor 106 oron separate transmission lines from those connecting the LEDs 222, 224to the oximeter board 440.

FIG. 5 illustrates an embodiment of the layout for the cable 104 whosecable information element 116 indicates that a first sensor informationelement 218 and a second sensor information element 134 should be foundin the sensor. In an embodiment, serial transmission line 446 connectsthe oximeter board 440 to the cable information element 116 as above.However, serial transmission line 446 also runs the length of cable 104and connects to second sensor information element 134 located in sensor106 in a multi-drop memory configuration. Oximeter board 440 may accesscable information element 116 and second sensor information element 134while running generally few transmission lines. If cable 104 isconnected to a sensor 106 that does not have second sensor informationelement 134, the oximeter board 440 may advantageously determine thatthe sensor is unauthorized and also advantageously may not enable thesensor. The rest of the circuits (i.e. transmission lines 442, 444;first sensor information element 218; and LEDs 222, 224) are the same asin FIG. 4.

It is to be noted that FIGS. 4 and 5 are representative embodimentsonly. These figures are not meant to be read as the exact or onlypossible locations of the elements discussed. For example, first sensorinformation element 218 and/or second information element 134 may or maynot be located in the same portion of the sensor. One or both or neithermay be placed in or near the connection housing 112. It is also possiblefor them to be at other positions in the sensor. The roles of each mayalso be switched with either one or both containing information aboutdata stored on the other. The numbering and discussion of theinformation elements is merely for ease of reference. It is alsoimportant to know that functionality of serial transmission line 446, aswell as transmission lines 442, 444, may be accomplished through othermeans, such as, for example, public or private communications networksor computing systems, or various wired or wireless communications.

Requirement Tables

In an embodiment, an information element 116 includes data allowing theconnection of both types of sensors depicted in FIG. 2 and FIG. 3. Thus,either a sensor 106 with only first information element 218 or one withboth first information element 218 and second information element 134could be connected as authorized sensors. In an embodiment, cableinformation element 116 may include a sensor requirement table asillustrated in Table 1 below. A sensor requirement table may listdifferent types of attachable accessories (such as the sensors generallydiscussed) and designate which version of such sensors can beauthorized. This may be accomplished through a single bit for each type.For example, as shown in Table 1, cable information element 116 mayinclude a table with a list of bits designating whether or not anattached sensor must have a second information element 134—here a 1indicates the second information element 134 is required, while a 0indicates an attached accessory may have either the first informationelement 218 or both information elements. As shown in this example,disposable sensors must include the second information element 134, butreusable or combination sensors may include one or both sensorinformation elements. Any of a number of sensor or other accessories maybe allowed or disallowed in such a manner. It is understood that thefirst sensor information element 218 must be capable of identifying thetype of sensor that it is a part of for comparison to the requirementtable, in such an embodiment.

TABLE 1 Disposable 1 Reusable 0 Combination 0 Adult 1 Neonatal 0 . . . .. . Override 0

Furthermore, in an embodiment, the requirement table may include anoverride bit or entry. The override bit preferably allows the attachmentof both kinds of accessories for all types, regardless of the currentvalues listed in the rest of the table. In such an embodiment, theoverride bit may allow diagnostics, testing, and the like without havingto separately keep track of or lose the settings for the variousaccessory types. Those of skill in the art will understand from thisdisclosure that the requirement table functionality may be implementedin a number of ways. For example, the table may be stored in anaccessory information element, such as cable information element 116,may be included in the monitor 102, and the like. Additionally therequirement table may be implemented as a table, linked list, array,single, multi-bit variable, or the like, and each entry may comprise oneor more bits to store the information. In one embodiment, therequirement table may be stored on an EPROM, which may allow the tableentries to be set only once. In another embodiment, an EEPROM or otherrewritable memory may allow each table entry to be altered more thanonce.

Site Licenses

The transfer of accessories from location to location, the sale of usedaccessories, and the like can also make quality control more difficult,such as by making accessory use hard to track. As such, it is alsopossible to help maintain quality control by recording or maintainingsite licenses, so that accessories, once used, can be tracked to theirfirst use location or maintained at a specific location.

Many patient monitors have an associated device ID, typically this is asoftware ID, but IDs coded into hardware are also possible. In anembodiment of the present disclosure where the monitor has such an ID,accessory use may be tracked or controlled through use of the monitorID. A general example will be set forth before turning to a specificembodiment according to the figures. When an accessory having aninformation element is plugged into the monitor having a monitor ID, themonitor may check to see if a monitor ID has been written to a portionof the information element. If not, the monitor may cause its ownmonitor ID to be written to the information element. From this point on,any monitor connected to that accessory will be able to determine themonitor of first use. If the accessory should later fail, an accessoryor patient monitor manufacturer may then be able to determine where itwas first used and if it was transferred to another location. In anembodiment, accessories may be tied to specific monitors or sets ofmonitors, such as to aid in keeping an accessory at a particular site orlocation. Once an accessory is used with a specific monitor, eachmonitor to which it is subsequently attached can read the monitor ID anddetermine if the monitor with which it was first used is part of thecurrent monitor's grouping (e.g. a site license). Monitors can beprogrammed to recognize monitor IDs from a specific site (such as onehospital, a health system, etc.), a geographic area (such as bycountry), an Original Equipment Manufacturer (OEM), combinations of thesame, and the like—anywhere from a single recognized monitor (itself) toany number of monitors. In an embodiment, the information element mayinclude at least a portion with write once capability, such as an EPROM,so that the monitor ID that is first written to the information elementcannot be changed.

A specific embodiment utilizing an oximeter example will now bediscussed in reference to the Figures. In looking to FIGS. 5 and 7,oximeter board 440, has a monitor ID (not shown). When, for example,cable 104, having cable information element 116 is connected to oximeterboard 440, the oximeter board may query cable information element 116(block 760). If cable information element 116 has not been used before,in an embodiment, it will have free space to which data may be written(block 762, branching with no monitor ID found). Oximeter board 440 willthen cause monitor ID to be written to the cable information element(block 764). (In an embodiment, a similar process may take place withsensor 106 and second sensor information element 134.) The monitor IDwritten to the cable information element 116 is preferably persistent,so as to remain when the cable 104 is disconnected from oximeter board440. During each subsequent use of the cable 104, oximeter board 440will be able to read the monitor ID from cable information element 116(blocks 760, 762, branching with a monitor ID found). In an embodiment,the patient monitor then compares the monitor ID found with a listaccessible by the oximeter board 440 (block 768). The oximeter board mayrespond according to the results of that ID comparison. For example, ifthe monitor ID found on the cable 104 is not acceptable, a warning maybe generated or the oximeter board may not allow readings using thecable (block 770). Alternatively, if the cable contains an acceptablemonitor ID, the oximeter may perform monitoring using the cable 104(block 772).

For example, a hospital may have a site license that allows the cablesit purchases to be used on any of its own oximeters. Each oximeter board440 has its own monitor ID, but also has a list of monitor IDs of theother monitors the hospital owns or licenses. Once a cable is used withone of the hospital's oximeters, the cable 104 may only be able to workwith that hospital's other oximeters. In one embodiment, connecting sucha cable 104 to another hospital's oximeter will trigger a visual oraudible warning. In another embodiment, use of the cable may bedisabled. This type of quality control can help both the originalhospital and the subsequent hospital in this example. If a cable fails,the first hospital can report it to the supplier who may be able todetermine if the first hospital's oximeters may be the source of anunderlying problem. On the other hand, the second hospital may bealerted to used accessories that may be more likely to fail.

There are numerous alternatives for such a “site license” qualitycontrol. For example, oximeters or other patient monitors may havespecific lists of acceptable monitor IDs, monitor IDs may be the samefor all patient monitors in a group, patient monitors may have a rangeof acceptable monitor IDs, patient monitors may have a specific equationor algorithm that determines acceptable monitor IDs, and the like. Insome embodiments, accessories may record monitor IDs from all monitorsto which they are connected, allowing manufacturers, suppliers, endusers and the like to track the monitor's use.

Upgrade Tool

One specific accessory that may be utilized in a patient monitor systemsuch as that described in the previous “Requirements Table” and “SiteLicense” sections is an upgrade tool. Upgrade tools connect to anaccessory port of a patient monitor to aid in reprogramming or updatingthe patient monitor without the need for an additional port, taking thepatient monitor apart, returning it to the manufacturer and the like.Upgrade tools and a method for their use is generally disclosed in U.S.application Ser. No. 10/898,680, titled “Multipurpose Sensor Port” andfiled on Jul. 23, 2004, incorporated herein by reference and made a partof this specification.

Often times a patient monitor or a specific control board will be madeby an OEM that is capable of monitoring a host of patient parameters.Making all its boards the same can often reduce costs for an OEM. TheOEM, however, may license only certain aspects of the patient monitor orcontrol board to various users. For example, one hospital may obtain theequipment and license it to monitor SpO₂, while another may license onlyCO monitoring, and the like. Should a user wish to change its monitoringcapabilities, the OEM does not need to sell it new equipment, instead itcan just enable or disable various features of the patient monitor orcontrol board that it has already provided to that user through use ofan upgrade tool. It is important that such an upgrade tool only beenabled for specific patient monitors, however. For example, if hospitalA pays for upgrades to its licenses, the OEM would like to ensure thatthe upgrade tool provided to A is not used to upgrade hospital B'spatient monitors. The monitor ID recording discussed above is one waythat this restriction can be accomplished. For example, an upgrade toolmay record the monitor ID of the first monitor to which it is attached.In most instances, this will be a patient monitor from the properupgrade group. Once this monitor ID is recorded, the upgrade tool maythen only be enabled by any other patient monitor in the correct group,like any other accessory.

In other embodiments, an upgrade tool may contain an information elementthat stores the monitor IDs of all patient monitors for which an upgradehas been paid. The upgrade tool and patient monitor can then compare IDsto determine if the patient monitor qualifies for the upgrade. Asanother alternative, an upgrade tool may have a predetermined ID and allOEM patient monitors or boards that may utilize that upgrade tool may beloaded with an ID or software sufficient to match to the upgrade tool'sID during or sometime after manufacture. In other embodiments, a patientmonitor may be upgraded by connection to a network, such as bytelephone, cable, DSL, USB, FireWire, and the like. Additionally, in anembodiment, a patient monitor may allow a user to enter the monitor ID,such as via a keypad, keyboard, or touch screen interface.

An upgrade tool may be used to alter one or more requirements tables aswell. However, it is also possible, in an embodiment, to program one ormore accessories themselves to amend requirements tables or upgradeother programming. For example, a sensor information element 134 mayinclude programming to alter a requirement table stored in a cableinformation element 116 once the components are connected and readiedfor monitoring.

Wireless Identification

Embodiments of the foregoing information elements use electricalconnections to facilitate communication between the patient monitors andthe information elements. This is also true in patient monitors thatutilize disposable and reusable elements (such as pictured in FIG. 1).In sensors such as FIG. 1, it is often advantageous to control thequality of the disposable portions to reduce problems that may arisefrom inferior disposable portions, such as faulty attachment, improperalignment of sensor components, contamination of the measurement sitethrough ambient light or physical contaminants, and the like. However,maintaining an electrical connection across the reusable/disposablemating point may complicate quality control efforts.

Wireless communications may offer additional advantages to help reducereliance on electrical contacts and advantageously allow communicationbetween disposable and other system elements. Wireless solutions includepassive and active radio frequency identification (RF ID). Passivesolutions get their broad ordinary meaning known to one skilled in theart, including solutions that rely on induction from surroundingelectromagnetic waves, such as radio waves, to power the RF ID tag.Active solutions get their broad ordinary meaning known to one skilledin the art, including solutions that have an internal or external powersource, such as a battery, photovoltaic cell, or electrical transmissionlines to an exterior source of power.

A RF ID solution suitable for the purposes discussed here is generallycommercially available. However, a brief discussion of the generaltechnology is instructive. A basic RF ID tag includes an informationelement, such as an integrated circuit, coupled with an antenna. Theantenna receives signals from a reader device capable of acquiring datafrom the integrated circuit of the tag. In passive RF ID, the incomingradio frequency energy from the reader device induces sufficientelectrical current to power the information element and transmit aresponse indicative of the information stored on the informationelement. In active RF ID, a battery or other power source may be used tosupplement or provide the power for transmitting the response.

FIG. 6 illustrates an exemplary patient monitoring system incorporatingwireless authentication utilizing radio frequency identification inrelation to cable information element 116 and sensor information element134. In one embodiment of this disclosure the RF ID configuration ispassive, thereby simplifying a disposable portion of a sensor accordingto this disclosure. In another embodiment of this disclosure, the RF IDconfiguration may be active. While this creates a slightly morecomplicated cable, sensor or other accessory, there are advantages thatmay offset the complications. For example, active RF ID tags typicallyallow for greater memory and the ability to store data received from thereader. An active RF ID tag may also provide greater transmissiondistances.

Specifically looking to the differences in FIG. 6, oximeter board 440further comprises or is in communication with a reader 650 capable ofsending and receiving radio frequency signals to attached accessories.In the cable 104, information element 116 is now connected to a radiofrequency antenna 652 to form a cable RF ID tag 660. Similarly, in thesensor 106, second information element 134 is also connected to a radiofrequency antenna 654 to form a sensor RF ID tag 662. Because cableinformation element 116 and information element 134 may now communicatewith each other and/or with oximeter board 440 (via reader 650) throughradio frequency signals, there is no need to have serial transmissionline 446 as was previously connecting these elements.

To enable attached accessories in an embodiment utilizing thistechnology, oximeter board 440 directs reader 650 to send out a radiofrequency signal. In the cable 104, antenna 652 receives this signal,and redirects the energy to reply with a signal indicative of theinformation stored on cable information element 116. Incoming radiofrequency signals induce a current in cable information element 116 andprovide the power to transmit a response. Often this is done throughback scattering the carrier signal from the reader 650. Oximeter board440's reader 650 may also send out a radio frequency signal received byantenna 654 in sensor 106. Antenna 654 likewise redirects the energyreceived in accepting the signal to reply with a signal indicative ofthe information stored on information element 134. Reader 650 receiveseach of the signals generated by cable RF ID tag 660 and sensor RF IDtag 662 and communicates them to oximeter board 440. Oximeter board 440compares the received information and enables usage of cable 104 andsensor 106 for patient monitoring if it recognizes each as approvedaccessories.

It is notable that the workings of the RF ID system as in FIG. 6 havebeen discussed in relation to passive RF ID elements. It would bestraightforward for one of ordinary skill to modify either or both ofcable RF ID tag 660 and sensor RF ID tag 662 to work as active RF IDtags by addition of a power source such as a battery or electricaltransmission lines from the oximeter's power source. This may benecessary if the RF ID element needs to transmit more than anidentification code or other small amount of data.

It should also be understood that the site license and upgrade toolconcepts may also utilize wireless technology as described herein toread and write monitor IDs. In an embodiment, this may allow a patientmonitor to update associated accessories without need of attaching theaccessory to the patient monitor.

Although the patient monitor capable of maintaining quality control inan optical sensor is disclosed with reference to its preferredembodiments, the disclosure is not intended to be limited thereby.Rather, a skilled artisan will recognize from the disclosure herein awide number of alternatives for such a patient monitor. For example, theelements used to code and identify the sensor may be passive or activesuch as resistors, transistor networks, memory chips, or otheridentification devices like Dallas Semiconductor DS 1990 or DS 2401 orother automatic identification chips. As described above, first andsecond sensor information elements may be switched in variousembodiments, and one or the other may be included. Additionally, RF IDsolutions are not the only wireless solutions available; other passiveor active wireless communications may also be used such as thoseconforming to IEEE or Bluetooth® standards. It is also possible to alterthe connections between various accessories; for example, the sensor's106 male connection housing 112 and the cable's 104 female connectionhousing 150 may be reversed or may each have a male and femalecomponent. Furthermore, any of a number of accessories may includeelements as described herein. Such accessories may be disposable orreusable or may have portions that are disposable and others that arereusable. Accessories may include, for example, cables, sensors, batterypacks, data storage such as hard drives, flash drives, and the like,computer boards, and the like.

It is also noted that the disclosure herein discusses only a two LED,one photodetector configuration for straightforwardness of thedisclosure. One skilled in the art would know that more complex orvaried data may be retrieved through the addition of more LEDs or otheremitting devices and/or more photodetectors or other detecting devices.Such devices may continue to utilize a single first sensor informationelement 218 or multiple information elements, corresponding to varioussensor components, with or without a second sensor information element134. Additionally, other combinations, omissions, substitutions andmodifications will be apparent to the skilled artisan in view of thedisclosure herein. Accordingly, the present disclosure is not intendedto be limited by the reaction of the preferred embodiments, but is to bedefined by reference to the appended claims.

Additionally, all publications, patents, and patent applicationsmentioned in this specification are herein incorporated by reference andmade a part of the specification hereof to the same extent as if eachindividual publication, patent, or patent application was specificallyand individually indicated to be incorporated by reference.

What is claimed is:
 1. A method which determines if a physiologicalsensor is an approved sensor to be used with a patient monitoringsystem, the method comprising: communicating, using a current patientmonitoring system, with a sensor memory device of a physiological sensorattached to the current patient monitoring system, the sensor memorydevice having at least a persistent portion with write-once capabilitysuch that information written to the persistent portion cannot bechanged; when the physiological sensor has not previously communicatedwith any patient monitoring system, storing an identification of thecurrent patient monitoring system in the persistent portion of thesensor memory device; when the physiological sensor has previously beenconnected to and communicated with a previous patient monitoring systemand an identification of the previous patient monitoring system has beenstored in the persistent portion of the sensor memory device: readingfrom the persistent portion of the sensor memory device theidentification of the previous patient monitoring system; accessing amemory associated with the current patient monitoring system whichstores a list of identifications of approved patient monitoring systemsassociated with the current patient monitoring system; and determiningwhether the physiological sensor is approved for use with the currentpatient monitoring system by comparing the identification of theprevious patient monitoring system stored in the persistent portion ofthe sensor memory device and the identifications of approved monitoringsystems, wherein the physiological sensor is determined to be approvedif the identification of the previous patient monitoring system storedon the persistent sensor memory device is found among the list ofidentifications of approved patient monitoring systems; and receivingand using information indicative of a physiological condition from thephysiological sensor only when the physiological sensor is an approvedsensor.
 2. The method of claim 1, wherein the list of identifications ofpatient monitoring systems comprises patient monitoring systemsassociated with a site license.
 3. The method of claim 2, wherein thesite license is associated with a hospital.
 4. The method of claim 1,wherein the persistent portion of the sensor memory device of aphysiological sensor comprises an EPROM.
 5. The method of claim 1,wherein communicating with the sensor memory device of a physiologicalsensor comprises communicating with a single wire memory device.
 6. Themethod of claim 1, further comprising disabling the use of thephysiological sensor when the physiological sensor is not approved foruse.
 7. The method of claim 1, further comprising generating an alarmwhen the physiological sensor is not approved for use.
 8. A patientmonitor configured to communicate with physiological sensors ofdifferent types and receive and use information indicative of aphysiological condition from the physiological sensors afterverification of the sensor, the patient monitor comprising: a monitormemory configured to store a list of identifications of additionalpatient monitors which are associated with the patient monitor; and aprocessor configured to: communicate with a sensor memory device of aphysiological sensor, the sensor memory device having at least apersistent portion with write-once capability such that informationwritten to the persistent portion cannot be changed, receiveidentification information from the persistent portion of the sensormemory device of the physiological sensor, the identificationinformation including an identification of any previous monitoringsystems which have previously communicated with the physiologicalsensor, and access the monitor memory to determine whether thephysiological sensor is an approved sensor by comparing theidentification of any previous patient monitoring systems stored in thepersistent portion of the sensor memory device with the identificationsof patient monitors stored in the monitor memory, wherein thephysiological sensor is determined to be approved if the identificationof any previous patient monitoring system stored on the persistentportion of the sensor memory device is found among the identificationsof patient monitors systems stored on the monitor memory; wherein thepatient monitor is configured to receive and use information indicativeof a physiological condition of a patient only when the physiologicalsensor is determined to be approved, and wherein when the physiologicalsensor has not communicated with any previous patient monitors and noidentification information is stored in the persistent portion of thesensor memory device, the processor is further configured to alter thepersistent portion of the sensor memory device of the physiologicalsensor to include an identification of the patient monitor.
 9. Thepatient monitor of claim 8, wherein the sensor is an approved sensor ifthe sensor has not communicated with any previous patient monitor. 10.The patient monitor of claim 8, wherein the list of patient monitorsincludes identifications of patient monitors associated with a sitelicense.
 11. The patient monitor of claim 10, wherein the site licenseis associated with a hospital.